Multicast and Broadcast Service (MCBCS) is an optional feature, which refers to a network's ability to provide flexible and efficient mechanisms of sending common (the same) information content to multiple users using shared radio resources. When available and appropriate, this may use the MBS air interface feature of the IEEE 802.16e standard. The MBS framework may be used to offer real-time streaming applications or non-real time file transfer/download for store and play usage. The type of information transmitted may be any type of data, e.g., text, multimedia (e.g., voice), and streaming media. The MBS may deliver content to MBS user groups, based on local policy and subscription. The multicast groups membership can be static or dynamic; users can join and leave groups at any time. By using multicast broadcast services, it will greatly save resources and by supporting Macro diversity and MS to receive data while in idle mode, it also saves a lot of power at the MS side.
IEEE 802.16e defines that for multi-base station MBS, if a mobile station (MS) is in an idle mode, and moves into base station's (BS) in the same MBS zone, the MS may not have to re-enter the network and to re-establish a connection or a connection defined by MBS contents identifier to monitor the multicast and broadcast service flow. In addition, for the MCBCS services, it is a requirement from the operator to support MS to receive the same contents under idle mode, which gives many benefits including the power saving. In order to ensure that each BS will transmit the exact same content with the exact same order at all BSs, synchronization and macro diversity are needed.